Melt-blending polypropylene-co-ethylene (CPP) and Bionolle with polypropylene-grafted maleic anhydride (Modic) as a compatibilizer was done. The effect of variational Medic concentration on the compatibility was evaluated using ultimate strength data and SEM micrographs, while the true molecular compatibility over all blend composition ranges was examined by calculating and comparing the theoretical value of glass transition temperature with the experimental value. The results suggest that 15 wt % Medic appears to be an optimum concentration, as indicated by a relatively high ultimate strength over all blend composition ranges and formation of the so-called cocontinuous phase in the blend morphology. Additionally, the value of glass transition temperature calculated theoretically agrees quite well with the experimental value, indicating that at a certain blend composition, the blend sample was found almost compatible.